The present invention relates to crayons, and in particular, to crayons for coloring fabric.
A first box of crayons has, for generations of children, marked an initiation into the life of school and learning. For many children, it is a first experience of contacting paper with a writing instrument.
Crayons have historically contained a predominant concentration of paraffin, a wax such as Bee's wax or Carnauba wax, stearic acid and a non-toxic pigment to impart color. Crayons used in industry, however, do contain toxic pigments such as lead cromate.
The process by which the paraffin-based crayons are made includes mixing stearic acid and pigments with paraffin heated to 160.degree. F. Once mixed, and further heated to 210.degree.-250.degree. F., the molten solution is added to molds. When cooled, the crayons are removed from molds and packaged. The process of making crayons has been described in Chemical & Engineering News, Feb. 11, 1991 at 20.
Another crayon writing instrument includes the marking crayon. Unlike the crayon described above, the marking crayon imparts color when contacted with materials other than paper, such as fabric. One formulation of marking crayons includes hard soap, Bee's wax crude, spermatic crude, carbon black, and Prussion Blue pigment as described in The Chemical Formulary (1948) edited by H. Bennett. Another formulation described in The Chemical Formulary includes a carbamate and stearate mixture.
Use of the marking crayon frequently requires the fabric surface to be conditioned before contact with the marking crayon. Conditioning includes moistening the fabric.
Other fabric marking instruments include markers containing volatile organic chemicals and chemicals imparting odor when used. These markers are not for use by children and do not confer a permanent, bright mark.